Molecular determinants of pH regulation in the cardiac Na+-Ca2+ exchanger.

The cardiac Na+-Ca2+ exchanger (NCX) plays a critical role in the heart by extruding Ca2+ after each contraction and thus regulates cardiac contractility. The activity of NCX is strongly inhibited by cytosolic protons, which suggests that intracellular acidification will have important effects on heart contractility. However, the mechanisms underlying this inhibition remain elusive. It has been suggested that pH regulation originates from the competitive binding of protons to two Ca2+-binding domains within the large cytoplasmic loop of NCX and requires inactivation by intracellular Na+ to fully develop. By combining mutagenesis and electrophysiology, we demonstrate that NCX pH modulation is an allosteric mechanism distinct from Na+ and Ca2+ regulation, and we show that cytoplasmic Na+ can affect the sensitivity of NCX to protons. We further identify two histidines (His 124 and His 165) that are important for NCX proton sensitivity and show that His 165 plays the dominant role. Our results reveal a complex interplay between the different allosteric mechanisms that regulate the activity of NCX. Because of the central role of NCX in cardiac function, these findings are important for our understanding of heart pathophysiology

MAPPING THE INFORMATION ENVIRONMENT: LEGAL ASPECTS OF MODULARIZATION AND DIGITALIZATION

The Article highlights the language of the digital and the principle of modularization as the basic concepts which the further development of the information environment will have to pivot around, regardless of how conflicts between freedom and control are temporarily solved. Perceiving both the computer and the Internet as complex systems, the authors look at how modular design of these systems freed the functionality of applications from the physicality of infrastructures, describe the evolutionary gains adhering to modularity, and how to preserve them - elaborating on the issues of access to the cable platform for broadband Internet and to virtual networks for computer technology. Their second focus shows how digitalization of information makes possible the merger of content and its protection. Especially through the use of DRM systems, private actors can create right enforcement mechanisms independent of the State. The legal system therefore faces new and more complex relations between private will and public sovereignty. In such a merged system it is harder to maintain freedom - much like in the fusion of function and infrastructure

Estudo sobre as percepções na relação médico veterinário, tutor e estudante de medicina veterinária em relação à clínica veterinária de pequenos animais no hospital de clínicas veterinárias da UFRGS

Apesar de não existir exigências e padrões sobre o processo de comunicação na medicina veterinária, este conceito está mudando. Estudos indicam que para o médico veterinário obter sucesso econômico, por exemplo, pontos críticos como habilidade, conhecimento, aptidões e atitudes do profissional, incluindo a comunicação, devem ser considerados. A medicina veterinária tem sofrido mudanças significativas devido à incorporação dos animais como membros da família, aumentando as responsabilidades dos veterinários em atender e entender as expectativas dos clientes. O presente estudo foi realizado com o objetivo de compreender as percepções de estudantes de medicina veterinária, tutores de animais e veterinários sobre a relação médico veterinário – proprietário. Foi distribuído para cada categoria um questionário específico que buscava compreender a realidade sócio-econômica do entrevistado e as suas percepções sobre a relação tutor-veterinário. Com base nos resultados, apontaram não haver divergências significativas de exigência das características apontadas pelas três categorias (veterinários, estudantes e proprietários) para um bom atendimento do proprietário e seu animal pelo veterinário. Como características importantes para um atendimento de qualidade do veterinário, foram destacadas pelas três categorias o “conhecimento técnico”, “ser atencioso com o proprietário e seu animal”, “expor alternativas de terapêutica” e “habilidade com o animal”. Observou-se também que há a necessidade do aprimoramento do conhecimento das habilidades de comunicação durante a graduação, evidenciado tanto pelos estudantes, como pelos veterinários e que os mesmos concordam com a afirmação de que a universidade deveria incentivar este tipo de conhecimento. Este trabalho é um estudo piloto e mais estudos devem ser realizados para uma melhor compreensão da relação médico veterinário e proprietários de animais.Although there are neither requirements nor standards for the communication process in veterinary medicine, this concept is changing. Studies indicate that, in order to obtain economic success, critical issues such as the veterinarian’s skills, knowledge, capabilities and attitudes, including the communication skills, should be considered. Veterinary medicine has been going through significant changes due to the incorporation of animals as family members, increasing the responsibilities of veterinarians to meet and understand customers’ expectations. This study was conducted with the aim of understanding the perceptions of the relationship among the veterinary doctor and pet owners, in the case of veterinary students, animal tutors and veterinarians. A specific questionnaire was distributed for each category that sought to understand the socio-economic realities of the interviewed and their perceptions of the tutor-veterinarian relationship. Based on the results, showed no significant differences in requirement of the characteristics indicated by the three categories (veterinarians, students and owners) for a good veterinarian service. How important characteristics for a veterinarian's quality of care, were highlighted by the three categories the "technical knowledge", "be considerate of the owner and his animal", "expose therapeutic alternatives" and "skill with the animal." It is also noted that there is a need for improving the communication skills during graduation, what is evidenced both by students and by veterinarians. Both groups agree with the statement that the university should encourage this type of knowledge. This work is a pilot study and further studies should be conducted to better understand the relationship among veterinarian and pet owners

The RCK2 domain of the human BKCa channel is a calcium sensor

Large conductance voltage and Ca2+-dependent K+ channels (BKCa) are activated by both membrane depolarization and intracellular Ca2+. Recent studies on bacterial channels have proposed that a Ca2+-induced conformational change within specialized regulators of K+ conductance (RCK) domains is responsible for channel gating. Each pore-forming α subunit of the homotetrameric BKCa channel is expected to contain two intracellular RCK domains. The first RCK domain in BKCa channels (RCK1) has been shown to contain residues critical for Ca2+ sensitivity, possibly participating in the formation of a Ca2+-binding site. The location and structure of the second RCK domain in the BKCa channel (RCK2) is still being examined, and the presence of a high-affinity Ca2+-binding site within this region is not yet established. Here, we present a structure-based alignment of the C terminus of BKCa and prokaryotic RCK domains that reveal the location of a second RCK domain in human BKCa channels (hSloRCK2). hSloRCK2 includes a high-affinity Ca2+-binding site (Ca bowl) and contains similar secondary structural elements as the bacterial RCK domains. Using CD spectroscopy, we provide evidence that hSloRCK2 undergoes a Ca2+-induced change in conformation, associated with an α-to-β structural transition. We also show that the Ca bowl is an essential element for the Ca2+-induced rearrangement of hSloRCK2. We speculate that the molecular rearrangements of RCK2 likely underlie the Ca2+-dependent gating mechanism of BKCa channels. A structural model of the heterodimeric complex of hSloRCK1 and hSloRCK2 domains is discussed

Evidence of pituitary hypoplasia associated with partial central diabetes insipidus in a young Persian cat

Background: Congenital anomalies are an uncommon pituitary hypofunction cause associated to multiple hormone deficiencies. Congenital hyposomatotropism is often related to an inherited anomaly, characterized mainly by delayed growth. It is not uncommon to find associated thyroid-stimulating hormone and gonadotropin deficiencies. Pituitary malformation may be associated to progressive cystic lesion expansion. Central diabetes insipidus (CDI) is another rare disease associated to polyuria (PU) and polydipsia (PD) secondary to antidiuretic hormone (ADH) deficient secretion. The aim of this report is to describe a likely case of pituitary hypoplasia, associated with partial CDI in a cat. Case: A 9-month-old unneutered male Persian cat weighing 2 kg was presented due to severe polyuria and polydipsia associated with growth deficit when compared with its sibling. After clinical and laboratory evaluations during the months in which the patient was monitored, reduced serum concentration of insulin-like growth factor-1 (IGF-1), thyroid-stimulating hormone (TSH), thyroid hormones, and testosterone were documented, confirming the diagnosis of hyposomatotropism, hypogonadism, and secondary hypothyroidism. Furthermore, therapeutic diagnosis with desmopressin revealed partial central diabetes insipidus (CDI). As the sibling showed normal development aging 13-months, a radiographic examination of the forelimb (carpus) was performed on both cats. There was lack of growth plate fusion in the patient, without any other evidence of dysgenesis, whereas complete epiphyseal closure was observed in the sibling. Despite therapeutic prescriptions of desmopressin and levothyroxine, the owners refused further follow-up to the case. Discussion: Notwhistanding neuroimaging was not available for investigation of pituitary aspect in this particular case, the clinical symptoms added to the results of the complementary tests were consistent with pituitary hypoplasia, associated with hyposomatotropism, secondary hypothyroidism, hypogonadism, and partial CDI. Hyposomatotropism was presumably diagnosed based on the patient’s clinical characteristics, which included proportional growth delay, delayed tooth eruption, delayed growth plate fusion, associated with serum reduced IGF-1 results in comparison with its sibling. The report of low free T4 by equilibrium dialysis and of low total T4 levels, associated with low TSH levels, was considered compatible with secondary hypothyroidism. TRH stimulation test is considered the gold standard for secondary hypothyroidism diagnosis since low TSH could be secondary to assay’s low sensibility. However, normal TSH and thyroid hormone results in the sibling results ruled out this possible dismissed diagnose. The patient’s lack of sexual interest, associated with hypotestosteronemia and underdeveloped genitals (absence of penile spines and testicular hypoplasia), indicates hypogonadism. Finally, partial CDI diagnosis was demonstrated by cat’s partial ability to increase urinary specific gravity under water deprivation often made by the owners, as well as the response pattern to desmopressin therapy. Owing the lack of neurological signs expected to be associated with neoplastic or traumatic hypopituitarism etiology, hypoplasia hypothesis was raised. Quite often, patients with pituitary hypoplasia develop Rathke cleft cysts that might expand over time. In the present case, partial CDI was likely to be caused by the compression of the neurohypophysis by cystic formation secondary to adenohypophyseal hypoplasia since this kind of pituitary congenital anomaly does not justify per se neurohypophysis implications

Dynamic Palmitoylation of the Sodium-Calcium Exchanger Modulates Its Structure, Affinity for Lipid-Ordered Domains, and Inhibition by XIP

The transmembrane sodium-calcium (Na-Ca) exchanger 1 (NCX1) regulates cytoplasmic Ca levels by facilitating electrogenic exchange of Ca for Na. Palmitoylation, the only reversible post-translational modification known to modulate NCX1 activity, controls NCX1 inactivation. Here, we show that palmitoylation of NCX1 modifies the structural arrangement of the NCX1 dimer and controls its affinity for lipid-ordered membrane domains. NCX1 palmitoylation occurs dynamically at the cell surface under the control of the enzymes zDHHC5 and APT1. We identify the position of the endogenous exchange inhibitory peptide (XIP) binding site within the NCX1 regulatory intracellular loop and demonstrate that palmitoylation controls the ability of XIP to bind this site. We also show that changes in NCX1 palmitoylation change cytosolic Ca. Our results thus demonstrate the broad molecular consequences of NCX1 palmitoylation and highlight a means to manipulate the inactivation of this ubiquitous ion transporter that could ameliorate pathologies linked to Ca overload via NCX1

Dilution of seawater affects the Ca2 + transport in the outer mantle epithelium of crassostrea gigas

Varying salinities of coastal waters are likely to affect the physiology and ion transport capabilities of calcifying marine organisms such as bivalves. To investigate the physiological effect of decreased environmental salinity in bivalves, adult oysters (Crassostrea gigas) were exposed for 14 days to 50% seawater (14) and the effects on mantle ion transport, electrophysiology and the expression of Ca2+ transporters and channels relative to animals maintained in full strength sea water (28) was evaluated. Exposure of oysters to a salinity of 14 decreased the active mantle transepithelial ion transport and specifically affected Ca2+ transfer. Gene expression of the Na+/K+-ATPase and the sarco(endo)plasmic reticulum Ca2+-ATPase was decreased whereas the expression of the T-type voltage-gated Ca channel and the Na+/Ca2+-exchanger increased compared to animals maintained in full SW. The results indicate that decreased environmental salinities will most likely affect not only osmoregulation but also bivalve biomineralization and shell formation.Funding Agency European Union (EU) 605051 Swedish Mariculture Research Center, SWEMARC, University of Gothenburg Herbert & Karin Jacobssons Stiftelse 15/h17 Helge Ax:son Johnsons Stiftelse F18-0128 Portuguese Foundation for Science and Technology UID/Multi/04326/2019 Portuguese Foundation for Science and Technology UID/Multi/04326/2019 FCT, under the "Norma Transitoria" DL57/2016/CP1361/CT0020 DL57/2016/CP1361/CT0011info:eu-repo/semantics/publishedVersio

Association Between Recent Cannabis Consumption and Withdrawal-Related Symptoms During Early Abstinence Among Females With Smoked Cocaine Use Disorder

BACKGROUND The effects of cannabis on clinical outcomes of treatment services for other drug use disorders remains unclear. The primary aim of the current study was to investigate the effects of recent cannabis consumption on the severity of cocaine withdrawal and depressive symptoms during a 3-week inpatient treatment program for women with cocaine use disorder. The second goal of this study was to test the effect of recent alcohol or tobacco use on the aforementioned outcomes. METHODS This was a longitudinal study with 2 assessment time points: at enrollment and upon discharge from a medically managed intensive inpatient unit. The sample was composed of 214 early abstinence females with cocaine use disorder. Cocaine withdrawal and depressive symptoms were measured using the Cocaine Selective Severity Assessment (CSSA) and the Beck Depressive Inventory (BDI-II). Recent substance use was evaluated using the Addiction Severity Index (ASI-6). RESULTS Patients with cocaine use disorder and with frequent recent cannabis use reported higher severity of cocaine withdrawal and depressive symptoms after 3 weeks of inpatient treatment. Neither recent alcohol nor tobacco use was associated with increased CSSA or BDI outcomes, suggesting these substances play a minor role compared to recent cannabis use in affecting withdrawal-related symptoms. CONCLUSIONS The assessment of recent cannabis use may help identify patients in need of additional treatment to manage severe cocaine withdrawal symptoms and depressive symptoms during early abstinence